A cross-sectional study of methicillin-resistant Staphylococcus aureus at the equine-human interface.

The study explores the prevalence of methicillin-resistant Staphylococcus aureus (MRSA) bacteria in horses and their handlers. The findings indicate that horses have a higher prevalence of MRSA, presenting an occupational health risk for those working closely with these animals.

Study Design and Data Collection

The researchers adopted a cross-sectional study design. The data was collected from two sources:

• 150 swab samples from horses
• 50 nasal swab samples from the personnel working with the horses

These samples were then processed in mannitol salt broth for enrichment, a procedure known for amplifying the presence of the Staphylococcus aureus bacteria.

Identification and Confirmation of Bacteria

After the enrichment process, 175 swab samples turned the color of the broth from pink to yellow. This color change indicated the presence of S. aureus bacteria.

The identified samples underwent further processing on specific media such as mannitol salt agar, Staph-110, and blood agar. This additional processing, coupled with Gram’s staining, served to confirm the presence of S. aureus isolates.

Of the 175 confirmed S. aureus-positive samples, 150 were from horses and 25 were from humans.

Detecting MRSA

The researchers then identified MRSA isolates from the 175 confirmed S. aureus samples via antimicrobial susceptibility testing with the disc diffusion method.

Out of these, 87 samples were identified as MRSA, 81 of which were from horses and 6 from personnel.

Examination of Antibiotic Susceptibility

The study also examined the antibiotic susceptibility of these MRSA isolates. The antibiotics oxacillin and methicillin proved to be most resistant against MRSA, while linezolid was found to be the most sensitive.

Key Findings

The results of the study demonstrated a higher percentage positivity of MRSA in horses (54%) compared to the associated personnel (24%).

This led to the conclusion that the higher prevalence of MRSA in equines could present an occupational risk to the personnel who work closely with these animals. These individuals may be more likely to contract MRSA from horses due to the extensive contact involved in their work.